Gervinho is in the starting XI for Arsene Wenger's side as Lukas Podolski features as a substitute, while Nigel Adkins takes charge of the Royals for the first time at the Emirates
Szczesny has not started a game for the Gunners since the 2-1 defeat to Tottenham in the north London derby on March 3.
Per Mertesacker and Laurent Koscielny are preferred to Thomas Vermaelen meanwhile, with the Belgian also starting as a substitute.
Lukas Podolski is on the bench, while Gervinho starts alongside Santi Cazorla and Olivier Giroud.
Nigel Adkins takes charge of his first game as Reading manager with Pavel Pogrebnyak up front ahead of a five-man midfield featuring Hal Robson-Kanu, Jem Karacan, Mikele Leigertwood, Danny Guthrie and Jobi McAnuff.
Arsenal starting XI: Fabianski; Sagna, Mertesacker, Koscielny, Monreal; Rosicky, Arteta, Ramsey; Cazorla, Giroud, Gervinho.
Subs: Szczesny, Vermaelen, Jenkinson, Gibbs, Coquelin, Oxlade-Chamberlain, Podolski
Reading starting XI: Taylor; Kelly, Mariappa, Pearce, Shorey; Robson-Kanu, Karacan, Leigertwood, Guthrie, McAnuff; Pogrebnyak.
Subs: McCarthy, Gunter, Morrison, Akpan, McCleary, Le Fondre, Hunt.